It is possible that either the intracellular differences in the levels of the TCA cycle intermediates between pre-malignant and malignant bone marrow CD138+ plasma cells or the differences between the CD138- bone marrow mononuclear cells from MGUS and MM patients are more likely to be captured from extracellular assessments in the bone marrow plasma rather than the peripheral blood plasma. Here, SDC1 is linked to Miyoshi myopathy.